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From: Roland McGrath <roland@redhat.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
       David Howells <dhowells@redhat.com>, James Morris <jmorris@namei.org>,
       Hugh Dickins <hugh@veritas.com>
Subject: Re: ptrace && cred_exec_mutex (Was: [PATCH] ptrace:
	tracehook_unsafe_exec: remove the stale comment)
In-Reply-To: Oleg Nesterov's message of  Friday, 24 April 2009 18:39:49 +0200 <20090424163949.GA12035@redhat.com>
References: <20090423212250.GA22537@redhat.com>
	<20090423232717.975ABFC3C7@magilla.sf.frob.com>
	<20090424163949.GA12035@redhat.com>
Message-Id: <20090424193835.A765BFC3C7@magilla.sf.frob.com>
Date: Fri, 24 Apr 2009 12:38:35 -0700 (PDT)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 864
Lines: 27

> (change subject, add more CCs)
> 
> On 04/23, Roland McGrath wrote:
> >
> > > tracehook_unsafe_exec() doesn't need task_lock(), remove the old comment.
> >
> > Please make it instead say that cred_exec_mutex is held by the caller
> > through the exec.
> 
> Yes. Except it looks like ->cred_exec_mutex is never used in fact.
> 
> ptrace_attach() takes current->cred_exec_mutex ? iow, ptrace and exec
> use different locks ?

Good point!  That sure looks broken to me.  David?

Either that should be task->cred_exec_mutex, or Oleg and I
are completely confused about what cred_exec_mutex is meant for.


Thanks,
Roland
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